"use strict";
var num2 = 123;
num2 = "str";
var num3 = 123;
num3 = "asd";
//======================
/*
    null和undefined是其它类型的子类型
*/
// let num4: number;
// console.log(num4);
var num4;
console.log(num4);
//void没有任何类型 方法没有返回值
function run() {
    console.log(123);
}
run();
function run2() {
    console.log(123);
}
run2();
function run3() {
    return 123;
}
run3();
//never(null,和undefined)
var ab;
ab = undefine;
var ba;
ba = null;
var er = (function () {
    throw new Error("错误永远不会出现");
})();
